We create a Bose-Einstein condensate(BEC) of 87Rb atoms by runaway evaporative cooling in an optical trap.Two crossed infrared laser beams with a wavelength of 1064 nm are used to form an optical dipole trap.After precooling the atom samples in a quadrupole-Ioffe configuration(QUIC) trap under 1.5 μK by radio-frequency(RF) evaporative cooling,the samples are transferred into the center of the glass cell,then loaded into the optical dipole trap with 800 ms.The pure condensate with up to 1.5×105 atoms is obtained over 1.17 s by lowering the power of the trap beams.
正交模分裂(或真空R ab i分裂)是原子与光学腔构成的复合系统实现强相互作用的一个典型现象。本文理论研究了三能级原子介质与腔构成的复合系统,利用线性色散理论将腔内三能级原子自感应透明(E IT)介质的吸收和色散引入光学腔透射公式,非常直观清晰得到腔透射谱的三个分裂峰,它是由腔内E IT介质的吸收和色散特性使一个共振腔模分裂为三个腔模。该方法可以推广到腔内含有任意色散和吸收的介质。
We study ^(87)Rb Bose-Einstein condensation(BEC) loading into the pulse of the one-dimensional(1D) optical lattice experimentally.The lattice is turned on abruptly,held constant for a variable time,and then turned off abruptly.The measurement of the depth of the optical lattice is obtained by Kapitza-Dirac scattering.The temporal matter-wave-dispersion Talbot effect with ^(87)Rb BEC is observed by applying a pair of pulsed standing waves(as pulsed phase gratings) with the separation of a variable delay.
We report the experimental achievement of ^(87)Rb Bose-Einstein condensation in a magnetic trap with microwave and radio frequency(RF) induced evaporation.Evaporative cooling is realized by using 6.8 GHz microwave radiation driving the ^(87)Rb atoms to transit from the ground-state hyperfine state |F=2,m_F= 2〉to |F=l,m_F=1〉.Compared with RF-induced evaporation,^(87)Rb atoms are hardly to achieve pure condensate by microwave evaporation cooling due to the effect of atoms in the |F=1,m_F=1〉state being pumped back into the trapping |F=2,m_F=1〉state.
